Lithium-ion cells have a high energy density that has contributed to their use in laptop computers and other portable electronic devices. Electric vehicles (EVs), both hybrid and purely electric are starting to use these cells. One disadvantage of lithium-ion cells is the potential for a destructive thermo-chemical reaction. There have been widely reported incidents involving laptop computers and their battery packs getting dangerously hot. A laptop only uses a handful of cells whereas an EV pack might contain more than one hundred cells, multiplying the danger.
Extreme damage to property and life may be caused if a chain reaction of runaway energy-releasing events occurs. A chain reaction could start with one failed cell's destructive condition causing another nearby cell to also have a significant energy release, propagating the failure and so on, engulfing over one hundred cells in an EV. Attempts at solutions have focused on either improving the inherent characteristics of Li-ion cells or on improvements in mechanical packaging of the many cells making up a battery.
There is a need to reduce the probability of a battery-wide destructive chain reaction without counting on close to perfect cells and while keeping cost, weight, power density needs, and other practical factors in mind.